In the field of image forming techniques with an electrophotographying system, in recent years, a digital image formation with high accuracy can be achieved by an exposure technique with a short wavelength laser beam having a wavelength of 350 to 500 nm and the like (for example, refer to Patent documents 1 and 2). As a result, in addition to the development of conventional copying machines and printers for office, it becomes possible to provide an image forming apparatus for the printing technical field where a high-quality image is required.
However, even if fine electrostatic latent images are formed on an electrophotographic photoreceptor by the irradiation of a microscopic exposure beam whose dot diameter is shortened with a short wavelength laser beam, it has not been realize yet to provide finally-acquired images with sufficiently-high image quality.
Namely, if image exposure is conducted with an exposure beam, whose dot diameter is shortened with a short wavelength laser beam, for an electrophotographic photoreceptor which has be developed for exposure beam with a conventional long wavelength, image defects, such as black spots and image unevenness, appear conspicuously on formed images. As a result, microscopic dot images cannot be reproduced accurately. Accordingly, when image formation is conducted with a short wavelength exposure beam for a conventional electrophotographic photoreceptor, since image defects tend to take place, there is a need to solve these problems.